Kratzer I guess you deliberately fail to see the big picture.
There is a difference with a loving slap and a fistfight.
The woman of the video obviously went for latter. I don't approve it any more than you do.
Still I think that physical punishment is crucial in raising a child at certain stages of development. There are certain thigns that a child must learn not to do no matter how much he wants it. Failure in teaching those things may lead to the childs injury or death so if a child simply wont listen to reason or threats, he must be punished in a way that he learns he must respect you.
If the child learns that you're nothing to play with at an early enough age, he'll listen to your commands instead of doing whatever he wants. That way is the safest way for the child for sure.
I saw a document about the politically correct method to raise kids in my country. That involved 30 minute discussion with the child in the morning, negotiating what the kid should wear out. So in the end the child refused to put on warm clothing (-2C) and the parent let the child go out in a summer outfit, just because the child insisted and it was time to go to kindergarten. The parent couldn't say no, she couldn't force the kid to wear warm clothes no matter how he hated them, nothing.
That leaves the kid confused, first he was asked to do something he had no ability to decide himself yet, then he froze his bellybutton outside and probably got a flu as a result. Well, at least nobody endangered his ego and self-rule so he can grow up to be an arrogant selfish bastard who thinks he can do whatever he wants without anyone being able to stop him in the end.
Kids like that very often end up in a prison.